Balloon catheter

ABSTRACT

A balloon catheter includes an outer conduit having an outer surface, and an inner conduit having an outer surface. The inner conduit is suitable for passage over a guide wire, and the inner conduit is movably disposed within the lumen of the outer conduit. There is also a balloon having a proximal margin and a distal margin, such that the proximal margin of the balloon is attached to the outer surface of the distal tip of the outer conduit and the distal margin of the balloon is attached to the outer surface of the portion of the inner conduit that extends beyond the distal tip of the outer conduit. And there is a fluid port for introducing an expansion fluid into the annular space formed between the inner surface of the outer conduit and the outer surface of the inner conduit and into the lumen of the balloon, and for the removal of the expansion fluid.

RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.11/477,812 filed Jun. 30, 2006 which claims the benefit of priority toU.S. Application Nos. 60/695,668 filed Jul. 5, 2005 and 60/726,160 filedOct. 14, 2005, the entire contents of each of which are herebyincorporated by reference.

FIELD OF THE INVENTION

The present invention relates to a catheter system suitable for theretrieval of debris and other solid or liquid matter from body passages,and the removal of said matter from the body. More particularly, theinvention relates to catheter systems comprising two or moreconcentrically-arranged conduits and an inflatable element connectedtherebetween, wherein said inflatable element is arranged such that itmay entrap solid or liquid matter in an internal annular cavity.

BACKGROUND OF THE INVENTION

Catheters are used in various interventional procedures for deliveringtherapeutic means to a treated site (e.g., body organ or passageway suchas blood vessels). In many cases, a catheter with a small distalinflatable balloon is guided to the treated site. Once the balloon is inplace it is inflated by the operator for affixing it in place, forexpanding a blocked vessel, for placing treatment means (e.g., stent)and/or for delivering surgical tools (e.g. knives, drills etc.) to adesired site. In addition, catheter systems have also been designed andused for retrieval of objects such as stents from body passageways.

Two basic types of catheter have been developed for intravascular use:other-the-wire (OTW) catheters and rapid-exchange catheters. OTWcatheter systems are characterized by the presence of a full-lengthguide wire, such that when the catheter is in its in situ workingposition, said guide wire passes through the entire length of a lumenformed in, or externally attached to, the catheter. OTW systems haveseveral operational advantages which are related to the use of a fulllength guide wire, including good stiffness and pushability, featureswhich are important when maneuvering balloon catheters along tortuousand/or partially occluded blood vessels.

U.S. Pat. No. 6,039,721 describes a balloon catheter system comprisingtwo concentrically-arranged conduits, with a balloon connected betweenthe distal regions thereof. The catheter system permits bothexpansion/deflation of the balloon and alteration in the length of theballoon when in situ, such that the balloon may be moved betweenextended and intussuscepted conformations. The catheter system isconstructed in order that it may be use for two main purposes: firstly,treatment (i.e. expansion) of different-length stenosed portions ofblood vessels with a single balloon and secondly, the delivery of eitherstents or medication to intravascular lesions, wherein the stent ormedication is contained within the distally-intussuscepted portion ofthe balloon. When used for multiple, differing-length lesion expansion,the balloon is inserted into blood vessel in a collapsed, shortened,intussuscepted conformation, and is advanced until it comes to rest inthe region of the shortest lesion to be treated. The balloon is theninflated and the lesion treated (i.e. expanded). Following deflation ofthe balloon, the distal end of the catheter system is moved such thatthe balloon becomes positioned in the region of the next-shortest lesionto be treated. The effective length of the balloon is then increased bymoving the inner conduit in relation to the proximal conduit, followingwhich the balloon is again inflated and the lesion treated. In this way,a series of different length stenoses—in order from the shortest to thelongest—may be treated using a single balloon. When used for stentdelivery, the stent is pre-loaded into a proximal annular space formedas a result of balloon intussusception. The balloon is then moved to thedesired site and the stent delivered by means of moving the innerconduit distally (in relation to the outer tube), thereby “unpeeling”the stent from the catheter.

WO 00/38776 discloses a dual-conduit balloon catheter system similar inbasic design to that described above in relation to U.S. Pat. No.6,039,721. This catheter system is intended for use in a vibratory modein order to break through total occlusions of the vascular lumen. Inorder to fulfill this aim, the outer conduit has a variable stiffnessalong its length, while the inner conduit. In addition, the innerconduit while being intrinsically relatively flexible is stiffened bythe presence of axial tensioning wires. These conduit design featuresare used in order to permit optimal translation of vibratory movementsof the proximal end of the inner conduit into corresponding vibration ofthe distal tip thereof.

Rapid exchange (“monorail”) catheters typically comprise a relativelyshort guide wire lumen provided in a distal section thereof, and aproximal guide wire exit port located between the catheter's distal andproximal ends. This arrangement allows exchange of the catheter over arelatively short guide wire, in a manner which is simple to perform andwhich can be carried out by a single operator. Rapid exchange cathetershave been extensively described in the art, for example, U.S. Pat. Nos.4,762,129, 4,748,982 and EP0380873.

Rapid exchange catheters are commonly used in Percutaneous TransluminalCoronary Angioplasty (PTCA) procedures, in which obstructed bloodvessels are typically dilated by a distal balloon mounted on thecatheter's distal end. A stent is often placed at the vessel's dilationzone to prevent reoccurrences of obstruction therein. The dilationballoon is typically inflated via an inflation lumen which extendslongitudinally inside the catheter's shaft between the dilation balloonand the catheter's proximal end.

The guide wire lumen passes within a smaller section of the catheter'sshaft length and it is accessed via a lateral port situated on thecatheter's shaft. This arrangement, wherein the guidewire tube isaffixed to the catheter's shaft at the location of its lateral port,usually prevents designers from developing new rapid exchange catheterimplementations which requires manipulating its inner shaft. Forexample, extending or shortening the catheter's length during proceduresmay be advantageously exploited by physicians to distally extend thelength of the catheter into a new site after or during its placement inthe patient's artery, for example in order to assist with the passage oftortuous vessels or small diameter stenoses, or to allow in-situmanipulation of an inflated balloon at the distal end of the catheter.

The rapid exchange catheters of the prior art are therefore usuallydesigned for carrying out a particular procedure and theirimplementations are relatively restricted as a consequence of the needfor at least one catheter shaft to exit the catheter system laterally,between the proximal and distal ends of said system. Consequently, aneed exists for a rapid exchange catheter that overcomes the abovementioned problems and which allows expanding the range of applicationsof such catheters.

Despite the large number of different balloon catheter systems currentlyavailable, a need still exists for a system that can efficiently andsafely collect plaque debris and other particulate matter from the lumenof internal body passages such as pathologically-involved blood vessels.

The primary object of the present invention is, therefore, to provide aballoon catheter system capable of collecting samples and/or debris fromthe body treated site and reducing the risk of distal embolization ofany material that may be dislodged during inflation of the balloon atthe treated site.

Another aim is to provide such a system in which the balloon length maybe substantially shortened during use without unduly increasing internalpressure.

A further aim is to provide such a system in which the catheter tubingis of a construction suitable for withstanding the forces generatedduring balloon folding and unfolding.

Yet another aim is to provide such a system in which the balloon is of ashape and constructions that permits both optimal debris entrapment andlow-profile folding within the passages to be treated.

A further object of the present invention is to provide balloon cathetersystems having the advantages outlined hereinabove, wherein saidcatheter systems are OTW systems.

A further object of the present invention to provide a rapid exchangecatheter having an adjustable balloon length and shape which may bemodified during a procedure.

Yet another object of the present invention to provide a rapid exchangeballoon catheter wherein the shape and/or volume of a standard inflatedballoon may be adjusted during a procedure.

A still further object of the present invention to provide a rapidexchange balloon catheter capable of collecting samples and/or debrisfrom the body treated site and reducing the risk of distal embolizationof any material that may be dislodged during inflation of the balloon atthe treated site.

Other objects and advantages of the invention will become apparent asthe description proceeds.

SUMMARY OF THE INVENTION

The present invention is therefore primarily directed to a ballooncatheter system comprising at least one inner conduit and one outerconduit mutually disposed one inside the other, such that theirlongitudinal axes either coincide or are substantially parallel to eachother, said inner tube being movably disposed along a longitudinal (i.e.distal-proximal) axis wherein an inflatable element such as a balloon isattached between the distal regions of said conduits, the distal end ofthe balloon being attached to the distal region of the inner conduit,and the proximal end of the balloon being attached to the distal regionof said outer conduit. The catheter system is constructed such that thelongitudinal position of the inner conduit in relation to the outerconduit may be altered by means of moving the proximal end of the innerconduit (i.e. the end closest to the operator). In this way, thedistal-proximal length of the outer surface of the balloon may bealtered, such that the balloon may be caused to progressively movebetween an elongated, extended conformation and a shortened,terminally-intussuscepted conformation, wherein in the latterconformation, an open-ended inner cavity is created in theterminally-intussuscepted region of the balloon. In use, this innercavity may be employed to entrap particulate debris, liquids and otherobjects and substances and safely remove same from the body passage inwhich the balloon catheter system is inserted. The inflatable elementused in the presently-disclosed and described catheter system is of ashape that permits said element to meet the dual requirements ofeffective debris collection and low-profile delivery and retrieval.Thus, in one preferred embodiment the inflatable element is provided inthe form of a balloon having, in its inflated state, a tapered shapewith a rounded distal extremity. A further feature of thepresently-disclosed system is the presence of means for preventinginternal pressure changes that occur as a consequence of changing thelength and conformation of the balloon.

Thus, in one aspect, the present invention provides an OTW ballooncatheter system comprising an outer conduit; an inner conduit disposedwithin the lumen of said outer conduit such that the longitudinal axesof said inner and outer conduits are substantially parallel, andpositioned such that the distal tip of said inner conduit extends beyondthe distal tip of said outer conduit, wherein said inner conduit iscapable of being moved along its longitudinal axis in relation to saidouter conduit, and wherein the lumen of said inner conduit is suitablefor allowing the passage of a guidewire therethrough; an angioplasticballoon whose proximal margin is attached to the outer surface of thedistal tip of said outer conduit, and whose distal margin is attached tothe outer surface of the portion of the inner conduit that extendsbeyond the distal tip of said outer conduit, and wherein the distalportion of said balloon is capable of intussusception upon proximalmovement of said inner conduit in relation to said outer conduit; meansfor the introduction of an expansion fluid into the annular space formedbetween the inner surface of the outer conduit and the outer surface ofthe inner conduit and therefrom into the lumen of said balloon, and forthe removal thereof, and means for preventing pressure changes withinsaid annular space upon axial movement of said inner conduit in relationto said outer conduit.

In one preferred embodiment of the OTW balloon catheter system of thepresent invention, the inner and outer conduits are characterized bytheir ability to withstand axially directed forces in the range ofbetween 2 and 20 Newton without undergoing significant deformation. Inthe context of the present invention, the term “significant deformation”refers to changes in conduit length in excess of 5% of the total lengthof said conduit. While these conduits may be constructed of any suitablematerial capable of withstanding the aforementioned forces, in apreferred embodiment, the inner and outer conduits are constructedeither from a biocompatible polymer (which in a preferred embodiment isselected from the group consisting of braided nylon thread and nylonthread that has undergone orientation treatment) or from flexiblestainless steel tube.

In one preferred embodiment of the present invention, the balloon ischaracterized by having, in its inflated state, a pre-folding profile,i.e. it has shape which is capable of assisting and guiding theintussusception of the distal portion thereof upon proximal movement ofthe inner conduit in relation to the outer conduit.

In one particularly preferred embodiment of the catheter system, theaforementioned balloon pre-folding profile is achieved by manufacturingthe balloon such that it has (in its inflated state) a tapered shapewith a rounded distal extremity.

Preferably, the balloon is constructed from Nylon 12, Pevax or mixturesthereof. It is to be recognized, however, that the balloon may also beconstructed of any other suitable materials as are well known in theart, without deviating from the scope of the present invention asdefined in the claims.

In one preferred embodiment, the aforementioned means for preventingpressure changes comprises a syringe-like structure positioned at theproximal end of the catheter system, wherein the barrel of saidsyringe-like structure is formed by an expanded portion of the outerconduit, and wherein the plunger of said structure co-axially surroundsthe proximal end of the inner conduit, and is affixed thereto.

In another aspect, the present invention also provides a method forcollecting debris from an internal passage of a mammalian subjectcomprising the steps of:

a) inserting an OTW balloon catheter system as defined hereinabove overa guidewire into said internal passage, and advancing said catheteruntil the distal tip thereof has reached the site, at which it isdesired to collect debris;b) inflating the balloon with expansion fluid;c) pulling the inner conduit of said balloon catheter in a proximaldirection, such that the distal and/or proximal end(s) of said balloonintussuscept(s);d) deflating the balloon, thereby forming a cavity into which debris iscollected and entrapped; ande) removing the balloon catheter from the internal passage of thesubject, together with the entrapped debris.

In one preferred embodiment of the presently-disclosed method, theaforementioned internal passage is a vein or artery.

In another aspect, the present invention further encompasses rapidexchange (RE) catheter implementations in which the length of a distalsection of the catheter and the shape and/or volume of its distalballoon may be manipulated during procedures carried out therewith. Suchimplementations are ideally suited for use in debris collectionapplications, as described in connection with the OTW device of thepresent invention, hereinabove. However, the RE solutions of the presentinvention may also be used in any other RE application wherein it isnecessary to alter the length of a distally-placed balloon element.

Consequently, the present invention is also directed to a rapid exchangecatheter that permits axial movement of an inner conduit within an outerconduit comprising:

-   -   a) an outer conduit;    -   b) an inner conduit, suitable for total or partial passage over        a guide wire, wherein said inner conduit is disposed within the        lumen of said outer conduit such that the longitudinal axes of        said inner and outer conduits are substantially parallel,        wherein said inner conduit is capable of being moved along its        longitudinal axis in relation to said outer conduit and wherein        the proximal end of said inner conduit is angled such that it        pierces the wall of said outer conduit;    -   c) means for permitting said axial movement of said inner        conduit within said outer conduit, such that said movement is        not hindered by the passage of the angled proximal part of the        inner conduit through said outer conduit; and    -   d) means, situated at the proximal end of the outer conduit, for        causing axial pushing-pulling movements of said inner conduit.

In one preferred embodiment of the above-defined rapid exchangecatheter, the means for permitting unhindered axial movement of theinner conduit is provided by a sealing sleeve that is slidably fittedaround the external conduit, such that the angled proximal portion ofsaid inner conduit passes firstly through an elongated aperture in thewall of the external conduit, and secondly through a tightly sealedaperture in said sealing sleeve, such that upon axial movement of theinner conduit, said sealing sleeve is capable of preventing the transferof fluid through said elongated aperture.

In another preferred embodiment, the above means for permittingunhindered axial movement of the inner conduit is provided by a two-partinner conduit construction, whereby the first, proximal part of saidconstruction is non-movable, and wherein the second, distal part isslidably disposed within said proximal part.

In a further preferred embodiment, the abovementioned means forpermitting unhindered axial movement of the inner conduit is provided bya two-part inner conduit construction, whereby the first, proximal partof said construction is non-movable, and wherein the second, distal partis slidably disposed over said proximal part.

In a still further preferred embodiment, the aforementioned means forpermitting unhindered axial movement of the inner conduit is provided bya three-part inner conduit construction, whereby the first, proximalpart of said construction is non-movable, and wherein the second,intermediate part is non-movably disposed within said proximal part, andwherein the third, distal part is slidably disposed within saidintermediate part.

In another preferred embodiment of the rapid exchange catheter of thepresent invention, the means for causing axial movements of the innerconduit mentioned hereinabove comprise one or more wires, the distalend(s) thereof being attached to the inner conduit, and the proximalend(s) thereof extending beyond the proximal end of the outer conduit.

In another aspect, the present invention also provides a rapid exchangeballoon catheter system comprising:

-   -   a) an outer conduit;    -   b) an inner conduit, suitable for total or partial passage over        a guide wire, wherein said inner conduit is disposed within the        lumen of said outer conduit such that the longitudinal axes of        said inner and outer conduits are substantially parallel,        wherein said inner conduit is capable of being moved along its        longitudinal axis in relation to said outer conduit, wherein the        proximal end of said inner conduit is angled such that it        pierces the wall of said outer conduit, and wherein the distal        tip of said inner conduit extends beyond the distal tip of said        outer conduit;    -   c) an angioplastic balloon whose proximal margin is attached to        the outer surface of the distal tip of said outer conduit, and        whose distal margin is attached to the outer surface of the        portion of the inner conduit that extends beyond the distal tip        of said outer conduit, and wherein the distal and/or proximal        end portion(s) of said balloon are capable of intussusception        upon proximal movement of said inner conduit in relation to said        outer conduit;    -   d) means, situated at the proximal end of the outer conduit, for        causing axial pushing-pulling movements of said inner conduit;    -   e) means for the introduction of an expansion fluid into the        annular space formed between the inner surface of the outer        conduit and the outer surface of the inner conduit and therefrom        into the lumen of said balloon, and for the removal thereof;    -   f) means for preventing pressure changes within said annular        space upon axial movement of said inner conduit in relation to        said outer conduit; and    -   g) means for permitting axial movement of said inner conduit        within said outer conduit, such that said movement is not        hindered by the passage of the angled proximal part of the inner        conduit through said outer conduit.

In one preferred embodiment of the rapid exchange balloon cathetersystem defined hereinabove, said system is constructed such that thedistal portion of the balloon is capable of intussusception uponproximal movement of the inner tube in relation to the outer tube.

In one preferred embodiment of this aspect of the invention, the meansfor causing axial movements of the inner conduit comprise one or morewires, the distal end(s) thereof being attached to the inner conduit,and the proximal end(s) thereof extending beyond the proximal end of theouter conduit.

In another preferred embodiment of this aspect of the invention, themeans for preventing pressure changes comprises a plunger slidablydisposed within the proximal end of the outer conduit, wherein saidplunger is connected to the axial pushing-pulling means, such that uponoperation of said pushing-pulling means, said plunger is caused to slideeither distally or proximally, thereby changing the volume of the outerconduit.

Any suitable means may be employed for permitting unhindered axialmovement of the inner conduit in the above-defined rapid exchangeballoon catheter system. Preferably, however, these means are as definedin any one of the preferred embodiments disclosed hereinabove andclaimed hereinafter.

In particularly preferred embodiments of the RE catheter system of thepresent invention, the balloon shape and force resistancecharacteristics of the catheter tubing are as described hereinabove inconnection with the OTW systems, and as exemplified in the Examplesprovided hereinbelow.

It should be noted that in each of the embodiments of the cathetersystems of the present invention disclosed and described hereinabove, alubricant (such as silicone oil or mineral oil) may be present in orderto facilitate the mutual sliding of the various conduits.

In another aspect, the present invention also provides a method forcollecting debris from an internal passage of a mammalian subjectcomprising the steps of:

a) inserting a rapid exchange balloon catheter system as definedhereinabove into said internal passage, and advancing said catheteruntil the distal tip thereof has reached the site, at which it isdesired to collect debris;b) inflating the balloon with expansion fluid;c) pulling the inner conduit of said balloon catheter in a proximaldirection, such that the distal and/or proximal end(s) of said balloonintussuscept(s);d) deflating the balloon, thereby forming a cavity into which debris iscollected and entrapped; ande) removing the balloon catheter from the internal passage of thesubject, together with the entrapped debris.

In one preferred embodiment of the presently-disclosed method, theaforementioned internal passage is a vein or artery.

All the above and other characteristics and advantages of the presentinvention will be further understood from the following illustrative andnon-limitative examples of preferred embodiments thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is illustrated by way of example in the figures ofthe accompanying drawings, in which like references indicate similarelements and in which:

FIG. 1A schematically illustrates over-the-wire insertion of the ballooncatheter of the invention;

FIG. 1B shows a cross sectional side view of the balloon catheter of theinvention;

FIG. 1C schematically illustrates one embodiment of the syringe-likepressure-compensating device situated at the proximal end of thecatheter system;

FIG. 2 schematically illustrates the balloon catheter of the inventionwhen inflated at a treatment site;

FIGS. 3 and 4 schematically illustrate debris collection carried out bythe balloon catheter of the invention by folding the inflated balloonand deflating it thereafter; and

FIG. 5 is a flowchart demonstrating the steps of an interventionalprocedure performed with the balloon catheter of the invention that mayinvolve sample collection;

FIG. 6 schematically illustrates the four balloon designs that wereanalyzed and compared in the finite element analysis study: a. Standard20° tapering; b. 20° tapering with smooth round ending; c. Round ending;d. Round ending with initial retracting;

FIG. 7 graphically depicts the displacement vs. retracting force for thefour balloon shapes, compared at an inflation pressure of 6 atmospheres.

FIG. 8 graphically depicts the maximum force generated in the cathetertubes following balloon folding, measured for different ballooninflation pressures;

FIGS. 9A to 9C show longitudinal section views of a rapid exchangecatheter according to one preferred embodiment of the invention whereinthe distal section of the inner tube comprise an internal slidable tube;

FIGS. 9D and 9E demonstrate utilizing different balloons for differentmanipulations thereof;

FIG. 9F demonstrates a piston-like construction for preventing pressureaccumulation within the catheter during retraction;

FIGS. 10A to 10C show longitudinal section views of a rapid exchangecatheter according to a second preferred embodiment of the inventionwherein the diameter of the distal section of the inner tube is adaptedto receive an internal slidable tube;

FIG. 11 shows a longitudinal section view of a rapid exchange catheteraccording to a third preferred embodiment of the invention wherein thedistal section of the inner tube comprise an external slidable tube;

FIG. 12 shows a longitudinal section view of a rapid exchange catheteraccording to a fourth preferred embodiment of the invention wherein thediameter of the distal section of the inner tube is adapted to bereceived in an external slidable tube;

FIG. 13 shows a longitudinal section view of a rapid exchange catheteraccording to a fifth preferred embodiment of the invention wherein thedistal section of the inner tube comprises a fixed inner tube on whichan external slidable tube is mounted;

FIGS. 14A to 14C show longitudinal section views of a rapid exchangecatheter according to a sixth preferred embodiment of the inventionwherein the inner tube of the catheter is encompassed in a slidableintermediate tube; and

FIGS. 15A to 15C show longitudinal section views of a rapid exchangecatheter according to a seventh preferred embodiment of the inventioncomprising a movable inner tube affixed to a slidable sealing sleeve.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The present invention is directed to a method and apparatus for removingobjects (such as atheromatous plaque debris) or collecting samples froma body passageway such as a blood vessel. The presently-disclosed methodand apparatus may also be used to expand a region of a body passageway(such as an atheromatous narrowing or occlusion of a blood vessel) inaddition to removing debris or other matter or objects therefrom. In apreferred embodiment of the invention, a balloon catheter that issuitable for carrying out common interventional procedures is adapted toenable the expansion of a region of a body passageway and collection ofobjects or samples from the treated site utilizing a unique design ofcatheter and balloon.

In the following description, the terms “conduit” and “tube” are usedinterchangeably.

Referring to FIG. 1A which illustrates the insertion of an OTW ballooncatheter 10 of the invention to a treatment site, for example bodypassage 20. As shown, balloon catheter 10 comprises an inner tube 17slidably positioned inside outer tube 18. The proximal (i.e., trailing)end of inner tube 17 comprises an entry port 12, which extends outwardlythrough orifice 29 provided at the proximal end of outer tube 18.Orifice 29 tightly fits around the outer surface of inner tube 17without gripping it, thereby allowing proximal and distal movements ofinner tube 17 while sealing the inner lumen of outer tube 18. Graduatedscale 19 may optionally be provided on the outer surface of inner tube17.

The proximal end of outer tube 18 further comprises a fluid port 11 forinjecting/removing inflation fluids to/from inner lumen of outer tube18, an over-pressure valve outlet 15 for discharging inflation fluidswhenever over-pressure conditions develop in the inner lumen of outertube 18, and an inner tube safety lock 14 adapted for gripping the outersurface of inner tube 17, thereby preventing proximal-distal movementsthereof relative to outer tube 18.

Over-pressure valve outlet 15 may include an over-pressure valve 16 forsealing the opening of over-pressure valve outlet 15 and for dischargingportions of inflating fluids therethrough whenever over-pressureconditions are reached in inner lumen of outer tube 18. It should berealized however that such over-pressure conditions may be resolved byother means. For example, an inflatable member (not shown) may beattached to the opening of over-pressure valve outlet 15, and in such animplementation over-pressure valve 16 may be eliminated. Moreover, outertube 18, or portions thereof, may be inflatable such that over-pressureconditions may be resolved by its expansion.

Inner tube safety lock 14 contacts the outer surface of inner tube 17via a tight orifice provided on the outer surface at the proximal end ofouter tube 18. As shown in the cross sectional view of FIG. 1B, a“U”-shaped gripping clip 24 may be attached to inner tube safety lock 14for gripping inner tube 17 therewith by pushing inner tube safety lock14 inwardly and fitting the arms of gripping clip 24 around the outersurface of inner tube 17.

As seen in FIG. 1A distal (leading) end of inner tube 17 extendsoutwardly via the distal opening of outer tube 18, into the body passage20. An inflatable member, for example non-compliant balloon 5, isattached to the distal ends of outer tube 18 and inner tube 17. Balloon5 is preferably made from a flexible resilient sleeve having conicalends having gradually decreasing diameters towards the tips of thesleeve. Balloon 5 is attached at circumferential attachment point 7 tothe outer surface near the distal tip of outer tube 18, and atcircumferential attachment point 6 to the outer surface near the distaltip of inner tube 17, such that it seals the distal opening of outertube 18.

As mentioned hereinabove, in one preferred embodiment of this aspect ofthe invention, the means for preventing pressure changes in theinflation fluid space comprises a syringe-like structure positioned atthe proximal end of the catheter system, wherein the barrel of saidsyringe-like structure is formed by an expanded portion of the outerconduit, and wherein the plunger of said structure co-axially surroundsthe proximal end of the inner conduit. Referring now to FIG. 1C, themechanism in this preferred embodiment consists of a barrel portion 26and plunger 17 a movably disposed therein and affixed to outer surfaceof inner tube 17. Plunger 17 a seals the inflation lumen of ballooncatheter 10, such that proximal movements thereof, responsive toproximal movements of inner tube 17, generate suction of inflation mediainto barrel portion 26.

With reference to the flowchart of FIG. 5, demonstrating the steps of aninterventional procedure performed with an OTW balloon catheter of theinvention. The procedure starts in step 50 wherein the balloon catheter10 is guided to the treatment site (e.g., over the wire). FIG. 1Ademonstrates over-the-wire insertion, wherein the insertion of ballooncatheter 10 is performed over guide wire 13. It should be clear,however, that the invention is not limited to one specific insertionmethod and that other appropriate and practicable insertion methods(e.g., using a guiding catheter) may also be used.

Next, in step 51, the operator inflates balloon 5 by injecting inflationfluids via fluid port 11 and the inner lumen of outer tube 18, asdemonstrated by fluid inflation arrows 8 a in FIG. 1A. When carrying outprocedures in body passage 20 as demonstrated in the FIGS. 1-4 inflationfluids are preferably injected into balloon 5 such that itscircumferential sides are expanded and pressed against the inner wall 21of body passage 20, as demonstrated in FIG. 2. The pressure insideballoon 5 in such conditions may be in general about 1-25 Atmospheres,preferably about 6 Atmospheres.

In this state in which the balloon catheter 10 is anchored, the innerlumen of inner tube 17 may now be utilized for operating in the treatedsite with different interventional tools (not shown), as may berequired. Step 52 indicates the possibility of performing procedures ifneeded, however, some procedures (for example angioplasty) may becompleted, or be near completion, once balloon 5 reaches its inflatedstate.

If it is determined in step 53 that a sample or other liquid or solidmatter should be collected from the treatment site, for example fluids,secretions, and/or debris 25, then in step 54 inner tube safety lock 14is pulled thereby releasing its grip from inner tube 17, as demonstratedby arrow 27 a in FIG. 2. In step 55 the inner tube 17 is retractedoutwardly (proximally) by the operator as shown by arrow 28. Duringretraction of inner tube 17 the distal tip of balloon 5 collapses andthe outer surface portions are folded inwardly over the distal tip ofinner tube 17 and thereafter over itself as further portions of theballoon collapse, as illustrated in FIG. 3.

Retraction of inner tube 17 and the resulting inward folding of balloon5 shorten the overall length of inflated balloon 5 which actuallyreduces the volume of inflated balloon 5. Consequently, the pressureexerted by the inflating fluids increases, resulting in a considerablepressure increase in balloon 5 and inner lumen of outer tube 18.Whenever the pressure in balloon 5 and inner lumen of outer tube 18reaches a certain set-point, inflation fluids are discharged viaover-pressure valve outlet 15, as shown by arrows 8 b in FIG. 3, suchthat the pressure in balloon 5 and inner lumen of outer tube 18 remainswithin a predetermined pressure range (e.g., 1-25 atmospheres). Duringthis step the operator can determine via graduated scale 19 the amountof length of inner tube 17 that has been retracted and in this waydetermine when to stop the retraction and prevent further axial movementof inner tube 17 (step 58) by pushing down inner tube safety lock 14, asindicated by arrow 27 b.

Next, in step 56, balloon 5 is deflated by retracting inflation fluidsvia fluid port 11, as indicated by arrows 8 c in FIG. 4. In result, thepressure inside balloon 5 and inner lumen of outer tube 18 issubstantially decreased, and balloon 5 is deflated. The reduction in thevolume of balloon 5 results in the formation of an inner cavity 40defined by the outer surface of the folded balloon section, as shown inFIG. 4. In step 57 the operator retracts balloon catheter 10 proximallysuch that portion of fluid/secretion and debris 25 confined within innercavity 40 are withdrawn with the balloon catheter 10 (not shown in thefigures). The debris, objects or samples collected may be easilycollected when the entire length of balloon catheter 10 is ejected fromthe body of the treated subject, by pushing the inner tube 17 distallyand unfolding the folded portions of balloon 5, thus restoring thedeflated state of balloon 5 (shown in FIG. 1A).

In view of the axially-directed stretching and buckling forces exertedon the inner and outer tubes during elongation and shortening of theballoon, said tubes need to be constructed such that they are able towithstand axially-directed forces in the range of between 2 and 20Newton without undergoing deformation. In order to achieve this aim, theconduits may be constructed of a braided material or of materials havinga defined molecular orientation. The approximate maximum forces that theinner and outer tubes need to withstand (for two difference size rangesof balloon) are as follows:

-   -   2.5-4 mm balloons: the tubing should withstand up to 500 g;        polymer tubing made of nylon or pevax reinforced during the        manufacturing process can be used.    -   4-5 mm (or larger) balloons: the tubing should withstand forces        up to 2 kg. In this case it will be necessary to use a braided        tube (polymer tube with metal mesh reinforcement).

Results for a representative study of the forces generated duringballoon folding are presented in Example 2, hereinbelow.

Outer tube 18 is preferably made from a biocompatible polymer type ofmaterial, such as polyurethane or nylon or PET, and may be manufacturedutilizing conventional methods, such as extrusion. The diameter of innerlumen of outer tube 18 is generally in the range of 0.5-2.0 mm(millimeters), preferably about 0.7 mm, and the diameter of fluid port11 is generally in the range of 2-6 mm, preferably about 4 mm. Thediameter of over-pressure valve outlet 15 is generally in the range of1-6 mm, preferably about 4 mm, and the entire length of outer tube 18 isgenerally in the range of 100-2000 mm, preferably about 1400 mm.

Inner tube 17 is preferably made from a biocompatible polymer type ofmaterial, such as polyurethane or nylon or PET, and it may bemanufactured utilizing conventional methods, such as extrusion. Thediameter of inner lumen of inner tube 17 is generally in the range of0.2-2.0 mm, preferably about 0.5 mm, and its entire length is generallyin the range of 100-2000 mm, preferably about 1500 mm.

While the diameter of orifice 29 provided at the proximal tip of outertube 18 should be adapted to provide appropriate sealing of inner lumenof outer tube 18 it should also close over the outer surface of innertube 17 such that inner tube 17 may be displaced therethrough withrelatively low frictional forces. For example, if the diameter of innertube 17 is 0.7 mm, then the diameter of orifice 29 should be 1.0 mm.

Balloon 5 is preferably a non-compliant or semi-compliant balloon suchas manufactured by Advanced Polymers (Salem, USA) and by InterfaceAssociates (CA). It may be manufactured utilizing conventional methodsknown in the balloon catheter industry from a non-compliance type ofmaterial such as Pebax or Nylon (preferably Nylon 12). Its length isgenerally in the range of 10-60 mm, preferably about 20 mm. The bodydiameter can vary from 2.0 mm to 5 mm for coronary artery applications,and be significantly larger for use in larger blood vessels. Preferably,the balloon should have a burst pressure within the range of 12-20atmospheres. The proximal and distal edges of balloon 5 are preferablyadhered to the outer surfaces of outer tube 18 and inner tube 17respectively, at circumferential attachment points 7 and 6 respectively,by utilizing a UV or thermobonding type of adhesive such as commonlyused in the art.

The shape of balloon 5 has been found by the present inventors to becritical in order for said balloon to fulfill its intended functions inthe presently-disclosed and claimed catheter system, namely:

-   -   i. to facilitate folding in such a way that the desired annular        space is formed at the distal end of the intussuscepted balloon,        by the application of the lowest possible retracting force;    -   ii. to present a low profile that will facilitate introduction        and withdrawal of the deflated balloon into and out of the        catheter system and body passage.

The materials and design of the balloon, especially the shape of thedistal taper and the relationship between the distal and the proximaltaper, thus allow the balloon to fold smoothly and with relatively lowpulling forces. This also insures that the balloon will fold only itsdistal side.

It appears, from modeling studies performed by the inventors, that atapered balloon with a smooth round ending folds best and has arelatively low retracting force, when compared to standard taperedballoon or a balloon with a round ending. In a particularly preferredembodiment, the balloon has a proximal taper cone shaped with a 15-17degree angle, and a 15 degree round cone distal taper, having a radiusof about 0.5 mm at the junction of the taper and the neck. The resultsof the aforementioned modeling studies are presented in Example 2,hereinbelow.

Inner tube safety lock 14 is preferably made from a biocompatiblepolymer such as Tecoflex; its length is generally in the range of 1-15mm, preferably about 5 mm. If, for example, the cross-sectional diameterof inner tube safety lock 14 is about 2 mm, then the orifice provided onthe outer surface of outer tube 18 through which inner tube safety lock14 accesses inner lumen of outer tube 18 is preferably about 2.4 mm forproviding suitable sealing of inner lumen of outer tube 18.

In another aspect, the present invention aims to provide rapid exchange(RE) catheter implementations in which the length of a distal section ofthe catheter and the shape and/or volume of its distal balloon may bemanipulated during procedures carried out therewith. Suchimplementations are ideally suited for use in debris collectionapplications, as described in connection with the OTW device of thepresent invention, hereinabove. However, the RE solutions of the presentinvention may also be used in any other RE application wherein it isnecessary to alter the length of a distally-placed balloon element.

In general, the RE catheter of the invention comprises an outer cathetershaft and an inner tube provided therein, wherein the lumen of saidinner tube may be accessed via a lateral port provided on the catheter'sshaft. In some of the preferred embodiments of the present inventiondescribed herein the inner tube of the catheter is affixed to thecatheter's outer shaft and the catheter's length and its balloon aremanipulated by a unique construction of the inner tube. In theseconstructions the catheter's inner tube may comprise a slidable distaltube that may be moved by the operator, distally or proximally relativeto the catheter's outer shaft, via a displacement rod attached thereto.Alternatively, the inner tube may be encompassed in a slidableintermediate tube which may be moved by the operator distally orproximally relative to the catheter's shaft.

In further embodiments of the invention a unique catheter constructionis developed in order to provide a movable inner tube affixed to aslidable sealing sleeve which allows the operator to move the inner tubedistally or proximally relative to the catheter's outer shaft andthereby manipulate its length and balloon.

FIG. 9 shows longitudinal section views of a first embodiment of therapid exchange catheter 610 of the invention wherein the distal end ofthe catheter's inner tube 614 comprises a slidable internal tube 613.Catheter 610 comprises a hollow outer shaft 66 comprising inner tube 614installed therein, and a slidable internal tube 613 placed in inner tube614 such that it protrudes distally via a distal opening thereof. Inthis construction the inner lumens of inner tube 614 and slidableinternal tube 613 are linked, thereby providing a continuous inner lumenending at a distal opening of slidable internal tube 613. Proximal endof balloon 611 a is attached to hollow outer shaft 66 at proximalattachment points 62 b provided around the outer surface of a distalsection thereof, and the distal end of said balloon is attached to theslidable internal tube 613 at distal attachment points 62 a providedaround the outer surface of a distal section of said slidable internaltube.

The lumen of inner tube 614 may be accessed via a lateral port 612provided on hollow outer shaft 66, between a distal and proximal endsthereof. Guide wire 65 (or other suitable accessories) may be insertedvia lateral port 612, advanced along the inner lumens of inner tube 614and slidable internal tube 613, and exit the inner lumen of slidableinternal tube 613 through a distal opening thereof.

Slidable concentric member 613 is adapted to fit into inner tube 614 andits diameter is preferably smaller than the diameter of inner tube 614such that it seals its distal opening while comfortably permittingdistal or proximal sliding of slidable internal tube 613 therethrough.Distal end portion of displacement rod 618 is attached to slidableinternal tube 613 thereby allowing the operator to move slidableinternal tube 613 distally or proximally relative to the catheter'souter shaft by pushing or pulling the proximal tip of displacement rod618.

Further sealing of the distal opening of inner tube 614 may be achievedby an annular gasket 64 attached to the surface of distal tip of innertube 614 such that a distal portion thereof is pressed against anannular portion of the outer surface of slidable internal tube 613.

The proximal portion of hollow shaft 66 comprises a fluid port 617 usedfor inflating or deflating balloon 611 a by an inflation fluidpressurized therethrough, an optional discharge valve 616 installed indischarge valve outlet 615, and rod aperture 619 for moving displacementrod 618 distally or proximally therethrough.

During a typical procedure RE catheter 10 is inserted into a bodytreatment site in which balloon 611 a may be inflated by an inflationfluid (designated by arrows 67 a in FIG. 9A) pressurized throughinflation fluid port 617, for effecting dilation or other procedures insaid treatment site and/or for anchoring said balloon therein. Thepressurized fluids pass via the hollow interior of hollow shaft 66 andreach the interior of balloon 611 a via a distal opening thereof. In itsinflated state, shown in FIG. 9B, the hollow interior of hollow shaft 66and the internal space of balloon 611 a are filled with pressurizedinflation fluid. Distal opening of inner tube 614 is sealed by slidableinternal tube 613 and (optionally) by gasket 64, thereby preventingleakage of pressurized inflation fluid thereinto. The pressure of theinflation fluid inside the system presses the gasket and improves thesealing provided by gasket 64. On the other hand, when the pressure ofthe inflation fluid is reduced the gasket's grip on the outer surface ofinner tube 614 is diminished which makes it easier for the gasket toslide over it.

The requisite procedure is typically carried out in the inflated stateof the balloon. By using the catheter of the invention for suchprocedures the operator may manipulate the catheter length and the shapeand volume of balloon 611 a by pulling displacement rod 618 b, therebymoving slidable internal tube 613 proximally further into inner tube614, as demonstrated by arrows 68 a. In result, the distal end ofballoon 611 a collapses and folds internally, as shown in FIG. 9C, whichincreases the pressure of the inflation fluid. Whenever the pressure ofthe inflation fluid inside the hollow interior of hollow outer shaft 66and in balloon 611 a is above a predetermined threshold value a slenderpassage of discharge valve is expanded to allow portions of inflationfluid to exit via discharge valve outlet 615 and thereby reduce thepressure of inflation fluid below said threshold value.

It should be noted that the use of pressure discharge elements 615 and616 constitutes merely one possible means of pressure reduction.

Hollow outer shaft 66 is preferably made from a polymer or metalmaterial, such as stainless steel (e.g. stainless steel 316), nitinol,or nylon, and it may be manufactured utilizing conventional methods,such as extrusion and laser cutting. The diameter of the hollow interiorof hollow shaft 66 is generally in the range of 1-2 mm (millimeters),preferably about 1.2 mm, and the diameter of inflation fluid port 617 isgenerally in the range of 2-6 mm, preferably about 3 mm. The diameter ofdischarge valve outlet 615 is generally in the range of 2-6 mm,preferably about 3 mm, and the entire length of hollow shaft 66 isgenerally in the range of 500-2000 mm, preferably about 1400 mm.

Inner tube 614 is preferably made from a flexible polymer or metalmaterial, such as pevax, nylon, stainless or nitinol and it may bemanufactured utilizing conventional methods, such as extrusion and lasercutting. The diameter of inner lumen of inner tube 614 is generally inthe range of 0.3-1 mm, preferably about 0.8 mm, and its entire length isgenerally in the range of 100-300 mm, preferably about 120 mm. Slidableinternal tube 613 is preferably made from a flexible polymer or metaltype of material, such as pevax, nylon, stainless or nitinol, and it maybe manufactured utilizing conventional methods (e.g. extrusion). Thediameter of inner lumen of slidable internal tube 613 is generally inthe range of 0.3-1 mm, preferably about 0.5 mm, and its entire length isgenerally in the range of 30-150 mm, preferably about 70 mm.

Balloon 611 a is preferably a type of non-compliant or semi-compliant orlow-compliant balloon such as manufactured by Interface Associates. Itmay be manufactured utilizing conventional methods known in the ballooncatheter industry from a biocompatible polymer type of material such asnylon 12. Its length is generally in the range of 5-50 mm, preferablyabout 20 mm, and its diameter is generally in the range of 2 to 12 mm,preferably about 3 to 5 mm. The proximal and distal edges of balloon 611a are preferably adhered to the outer surfaces of hollow shaft 66 andslidable internal tube 613, at circumferential attachment points 62 band 62 a respectively, by utilizing a low profile type of adhesion suchas thermo bonding, UV adhesives or acrylic manufactured by Locktight.

Displacement rod 618 may be manufactured from a metal wire or tube, suchas Stainless steel, Nitinol (Nickel Titanium) and polymers, having adiameter generally in the range of 0.2-2 mm, preferably about 0.5 mm,and length generally in the range of 500-2000 mm, preferably about 1600mm. Distal portion of displacement rod 618 may be adhered to the distalsection of slidable internal tube 613. Most preferably, distal portionof displacement rod 618 may be combined into the wall of internal tube613 thereby enhancing its rigidity and the grip provided therewith. Rodaperture 619 is adapted to allow conveniently moving displacement rod618 therethrough while providing suitable sealing of the hollow interiorof hollow shaft 66, thereby preventing leakage of inflation fluidtherefrom.

The inflation fluid is preferably a saline or a saline mixed withradio-opaque solution in different ratios. A syringe pump, or othersuitable inflation pumps, as commonly used in the field, may be used forintroducing the inflation fluid into the system. The pressure in thesystem in its various states is typically in the range of 1 to 25atmospheres.

While different discharge valves may be employed, discharge valve 616 ispreferably implemented by an annular element having an axial slenderpassage passing therein. In such implementation discharge valve 616 ismanufactured from an elastomer type of material, such as PVC by aninjection molding process. Its outer diameter is generally in the rangeof 2-6 mm, preferably about 4 mm, and its slender passage is designed toexpand whenever a pressure gradient of about 4 atmospheres evolvesbetween its ends.

Optionally, a proximal part 618 c of rod 618 is made to be wide enoughto occupy a volume of space within a proximal portion 66 b of hollowshaft 66, as sown in FIG. 9F. This piston-like construction 618 c allowsfor a syringe like action of rod 618 when retracted proximally, causingit to evacuate enough space in the proximal portion 66 b of the lumen ofhollow shaft 66. This extra space will then be filled by inflationfluid, thereby preventing pressure build-up within the catheter duringretraction of the rod 618.

As shown in FIG. 9C in its folded state distal cavity 63 a is obtainedby the inwardly folded distal sections of balloon 611 a. The volumeencompassed by cavity 63 a may be enlarged by (partially or entirely)deflating the balloon in this folded state, thereby filling the enlargedcavity with samples and/or debris from the treatment site. Differentdistal balloons may be designed to provide various balloon manipulationsas exemplified in FIGS. 9D and 9E.

For example, in balloon 611 b shown in FIG. 9E a proximal section of theballoon collapses and folds inwardly in response to movement of slidableinternal tube 613 proximally, thereby forming a proximal cavity 63 b.Such a result may be achieved by using a balloon which has higherresistance to folding at its proximal tapered end relative to its distaltapered end This can be achieved by using a balloon having differentangles at its distal and proximal tapers, wherein a steeper taperfacilitates its folding.

As another example, in balloon 611 ab shown in FIG. 9D both, proximaland distal, sections of the balloon are folded in response to movementof slidable internal tube 613 proximally, thereby forming a proximalcavity 63 b and a distal cavity 63 a. This result may be obtained forexample by using a balloon 611 ab with a symmetric shape—namely, theballoon having the same taper at its distal and proximal sides.

The procedure for using the RE balloon catheter of the present inventionmay be briefly described as follows:

-   -   1) Insertion of catheter into the body via peripheral blood        vessel by use of standard rapid exchange method, as is well        known in the art;    -   2) Inflation of the balloon by injecting inflation fluids via        fluid port 617 and the inner lumen of outer shaft 66, as        demonstrated by fluid inflation arrows 67 a in FIG. 9A; the        pressure inside balloon 611 may be in general about 1-25        Atmospheres, preferably about 6 Atmospheres.    -   3) If required, a sample or other liquid or solid matter (for        example fluids, secretions, and/or debris) may be collected from        the treatment site. Firstly, the safety lock mechanism fitted to        the proximal end of proximal displacement rod 618 is pulled,        thereby releasing its grip on said proximal displacement rod.        (The safety lock is not shown in FIG. 9A; a suitable type of        safety mechanism is, however, depicted in FIG. 1B and        described—in relation to the OTW device of the present        invention—hereinabove.) Displacement rod 618 is then pulled        proximally, thereby releasing retracting slidable internal tube        613 proximally, as demonstrated by arrow 68 a in FIG. 9B. During        retraction of slidable internal tube 613 by the operator the        distal tip of balloon 611 collapses and its outer surface        portions are folded inwardly over the distal tip of slidable        internal tube 613 and thereafter over itself as further portions        of the balloon collapse, as illustrated in FIG. 9C.    -   4) Retraction of slidable internal tube 613 and the resulting        inward folding of balloon 611 shortens the overall length of        inflated balloon 611 which actually reduces the volume of        inflated balloon 611. Consequently, the pressure exerted by the        inflating fluids increases, resulting in a considerable pressure        increase in balloon 611 and inner lumen of outer shaft 66.        Whenever the pressure in balloon 611 and inner lumen of outer        shaft 66 reaches a certain set-point inflation fluids can be        discharged via discharge valve 616, as shown by arrows 67 b in        FIG. 9B, such that the pressure in balloon 611 and inner lumen        of outer shaft 66 remains within a predetermined pressure range        (e.g., 1-25 atmospheres). Another exemplary option for        discharging pressure is by widening the proximal section 618 c        of rod 618 so it can act similar to a syringe action, as shown        in FIG. 9F. During this step the operator can determine via        graduated scale (not shown) provided on rod 618 the amount of        length of inner tube 614 that has been retracted and in this way        determine when to stop the retraction of inner tube 614. The        aforementioned safety lock is then returned to its locked state,        thereby preventing any further movement of displacement rod 618        and inner tube 614.    -   5) Subsequently, balloon 611 is deflated by retracting inflation        fluids via fluid port 617. As a result, the pressure inside        balloon 611 and inner lumen of outer tube 66 is substantially        decreased, and balloon 611 is deflated. The reduction in the        volume of balloon 611 results in enlargement of distal cavity 63        a.    -   6) The operator then retracts balloon catheter 610 proximally        such that portion of fluid/secretion and debris confined within        proximal cavity 63 a are withdrawn with the balloon catheter 610        (not shown in the figures). The debris, objects or samples        collected may be easily collected when the entire length of        balloon catheter 610 is ejected from the body of the treated        subject, by pushing the inner tube 614 distally and unfolding        the folded portions of balloon 611, thus restoring the deflated        state of balloon 611 (shown in FIG. 9A).

FIGS. 10A to 10C show longitudinal section views of a rapid exchangecatheter 620 according to a second preferred embodiment of the inventionwherein the diameter of a distal section 624 b of the inner tube 624 ais adapted to receive internal slidable tube 613. In this preferredembodiment the diameter of distal section 624 b of inner tube 624 a ismade relatively greater than the diameter of the proximal sectionthereof. Internal slidable tube 613 is designed to tightly fit intoproximal section 624 b and thereby seal its distal opening and preventleakage of inflation fluid thereinto. Alternatively or additionally,sealing may be achieved by gasket 64 attached to the distal section 624b of inner tube 624 a such that a distal portion thereof is pressedagainst an annular portion of the outer surface of slidable internaltube 613. Internal slidable tube 613 and the proximal section of innertube 624 a may be manufactured to have the same inner diameter, therebyforming a substantially homogenous inner lumen therebetween,particularly when internal slidable tube 613 is advanced all the wayinto distal section 624 b.

The structure and geometrical dimensions of elements of catheter 620 aremuch the same as those elements designated by the same numerals whichwere described above with reference to FIGS. 9A to 9C. Similarly,balloon 611 a may be inflated by inflation fluid (67 a) pressurized viainflation fluid port 617, and catheter's 620 length and the shape andvolume of balloon 611 a may be manipulated by moving displacement rod618 distally or proximally, as exemplified in FIGS. 10A to 10C.Different balloons may be designed to provide various balloon foldingconfigurations as exemplified in FIGS. 9D and 9E.

Inner tube 624 a may be manufactured by an extrusion and laser cuttingprocess from a plastomeric or metallic type of material, preferably fromnylon, PET or stainless steel. The diameter of the distal section ofinner tube 624 a is generally in the range of 0.3-2 mm, preferably about0.5 mm, and the diameter of slidable internal tube 613 is adapted toprovide tight fitting and the necessary sealing of distal opening ofinner tube 624 a when said internal tube is inserted thereinside.

FIG. 11 shows a longitudinal section view of catheter 630 according to athird preferred embodiment of the invention wherein the distal sectionof the inner tube 614 comprises an external slidable tube 613 a. In thispreferred embodiment the distal end of balloon 611 a is attached to theslidable external tube 613 a at distal attachment points 62 a providedaround the outer surface of a distal section of said slidable externaltube. The diameter of external slidable tube 613 a is made relativelygreater than the diameter of inner tube 614. External slidable tube 613a is designed to tightly fit over the outer surface of the proximalsection of inner tube 614 and to thereby seal its distal opening andprevent leakage of inflation fluid thereinto. Alternatively oradditionally, sealing may be achieved by gasket 64 attached to theproximal end portion of external slidable tube 613 a such that aproximal portion thereof is pressed against an annular portion of theouter surface of inner tube 614.

Using such external slidable tube 613 a in catheter 630 allows attachinga relatively shorter displacement rod 618 a to the proximal section ofsaid slidable tube 613 a. Alternatively or additionally, the distalportion of displacement rod 618 a may be combined into the wall ofexternal slidable tube 613 a along its longitudinal length, therebyenhancing its rigidity and the grip provided therewith.

The structure, geometrical dimensions of elements of catheter 630designated by the same numerals, and the method of manipulating itslength and balloon's volume and shape, are much the same as thoseelements and manipulating method which were previously describedhereinabove and therefore, for the sake of brevity, said elements willnot be further discussed at this point. External slidable tube 613 a maybe manufactured by an extrusion and laser cutting process from aplastomeric or metallic type of material, preferably from nylon orstainless steel. The diameter of external slidable tube 613 a is adaptedto provide tight fitting and the necessary sealing of distal opening ofinner tube 614 when said external slidable tube is mounted thereover.For example, the diameter of external slidable tube 613 a may be in therange of 0.3-2 mm, preferably about 0.8 mm.

A fourth preferred embodiment (640) of the invention is demonstrated inthe longitudinal section view shown in FIG. 12, wherein the diameter ofthe distal section 644 b of inner tube 644 a is adapted to be receivedin an external slidable tube 613 a. In this preferred embodiment thedistal end of balloon 611 a is attached to the slidable external tube613 a at distal attachment points 62 a provided around the outer surfaceof a distal section of said slidable external tube. The diameter ofdistal section 644 b of inner tube 644 a is made relatively smaller thanthe diameter of the proximal section thereof. External slidable tube 613a is designed to tightly fit over proximal section 644 b and therebyseal its distal opening and prevent leakage of inflation fluidthereinto. Alternatively or additionally, sealing may be achieved bygasket 64 attached to the proximal end of External slidable tube 613 asuch that a proximal portion thereof is pressed against an annularportion of the distal section 644 b of inner tube 644 a.

The external slidable tube 613 a of catheter 640 allows attachment of arelatively shorter displacement rod 618 a to the proximal section ofsaid slidable tube 613 a. Alternatively or additionally, the distalportion of displacement rod 618 a may be combined into the wall ofexternal slidable tube 613 a along its longitudinal length, therebyenhancing its rigidity and the grip provided therewith.

The structure, geometrical dimensions of elements of catheter 640designated by the same numerals, and the method of manipulating of itslength and balloon's volume and shape, are much the same as thoseelements and the manipulating method which were previously describedhereinabove and therefore will not be further discussed here. Inner tube644 a may be manufactured by an extrusion and laser cutting process froma plastomeric or metallic type of material, preferably from nylon orstainless steel. The diameter of the distal section 644 b of inner tube644 a is generally in the range of 0.3-2 mm, preferably about 0.5 mm,and the diameter of external slidable tube 613 a is adapted to providetight fitting and the necessary sealing of distal opening of inner tube644 a when said external tube is mounted thereover.

In a fifth preferred embodiment of the invention, illustrated in thelongitudinal section view shown in FIG. 13, an external slidable tube613 a is mounted over a inner tube 654 b protruding distally through adistal opening of fixed inner tube 654 a of catheter 650. In thispreferred embodiment the distal end of balloon 611 a is attached to theslidable external tube 613 a at distal attachment points 62 a providedaround the outer surface of a distal section of said slidable externaltube. A proximal end portion of fixed inner tube 654 b is fitted into adistal opening of inner tube 654 a, such that it seals said distalopening and most of its longitudinal length protrudes distally therefrominto the hollow interior of hollow shaft 66. The diameter of externalslidable tube 613 a is adapted to tightly fit over the external surfaceof fixed inner tube 654 b, thereby sealing its distal opening whileallowing it to be easily moved distally or proximally thereon by theoperator.

Sealant 64 c may be applied to the proximal end of fixed inner tube 654b in order to provide enhanced sealing of the distal opening of innertube 654 a. Sealing of the distal opening of fixed inner tube 654 b maybe achieved by an annular gasket 64 attached to the proximal tip ofexternal slidable tube 613 a such that a proximal portion thereof ispressed against an annular portion of the outer surface of fixed innertube 654 b.

Gaskets 64 can be made of a flexible material such as silicone orpolyurethane. Alternatively, gaskets 64 may be implemented by an addedlubricant such as mineral oil or silicone oil which improves the slidingbetween the tubes. The sealing may be further increased by increasingthe pressure in the balloon.

It should be noted that tubes 613 a and 654 a may be fixed tubes suchthat tube 654 a is fixed to the shaft 663 and tube 613 a is fixed to thedistal neck of balloon 611 a, such that tube 654 b can slide into bothtubes.

The structure, geometrical dimensions of elements of catheter 650designated by the same numerals, and the method of manipulating of itslength and balloon's volume and shape, are much the same to thoseelements and manipulating method which were previously describedhereinabove and therefore will not be discussed here, for the sake ofbrevity. Fixed inner tube 654 a and external slidable tube 613 a may bemanufactured by an extrusion and laser cutting process from aplastomeric or metallic type of material, preferably from nylon orflexible metal. Their diameters are adapted to provide tight fitting andthe necessary sealing of distal openings of inner tube 654 a and offixed inner tube 654 b.

FIGS. 14A to 14C show longitudinal section views of a sixth preferredembodiment of the invention in which the inner tube 64 of catheter 660is encompassed in a slidable intermediate tube 633 b. In this preferredembodiment the distal end of balloon 611 a is attached to the slidableintermediate tube 633 b at distal attachment points 62 a provided aroundthe outer surface of a distal section of said slidable intermediatetube. Horizontal opening 638 is provided on an upper side of slidableintermediate tube 633 b. Tube 64 protrudes upwardly through horizontalopening 638 towards the upper side of hollow shaft 66 at the location inwhich it is affixed thereto and provide an access to its lumen vialateral port 612.

During a procedure balloon 611 a may be inflated by pressurized fluid(designated by arrows 67 a in FIG. 14A) provided via inflation fluidport 617. As illustrated in FIG. 14B, pressurized fluid passes throughthe hollow interior of hollow shaft 663 into the internal space ofballoon 611 a. The catheter and its balloon in the inflated state areillustrated in FIG. 14B. The proximal section of intermediate tube 633 bbetween horizontal opening 638 and the proximal end of intermediate tube633 b may be sealed by a sealant 666 in order to prevent entry ofinflation fluids thereinto. Whenever the pressure in balloon 611 a andhollow interior of hollow shaft 663 is greater than a predeterminedthreshold value, a portion of inflation fluids are discharged viadischarge valve 616 installed in discharge valve outlet 615.

The proximal section of intermediate tube 633 b protrudes proximally viaproximal opening 665 provided at the proximal end of shaft 663. Proximalopening 665 is designed to conveniently allow the sliding ofintermediate tube 633 b therethrough while providing suitable sealingthereof and preventing leakage of inflation fluid therefrom.Manipulation of the catheter's length and its balloon's shape and volumeare performed by sliding the intermediate tube 633 b proximally ordistally relative to the catheter's shaft.

For example, after inflating balloon 611 a the operator may pull theproximal section of intermediate tube 633 b (designated by arrow 68 a inFIG. 14B) thereby causing distal section of balloon 611 a to collapseand fold inwardly and deform cavity 63 a, as illustrated in FIG. 14C.Horizontal opening 638 is adjusted to allow sliding intermediate tube633 b proximally into a state in which attachment point 62 a reachesproximal end of shaft 663, and on the other hand, to allow slidingintermediate tube 633 b sufficiently distally and enable stretching thefull length of balloon 611 a.

Intermediate tube 633 b may be manufactured by extrusion or lasercutting processes, from a plastomer or metallic type of material such asnylon, Teflon, or flexible stainless steel. The diameters of inner tube664 and of intermediate tube 633 b are adapted to allow insertion ofinner tube into the lumen of intermediate tube 633 b while providingsuitable sealing thereof and preventing leakage of inflation fluidsthereinto. For example intermediate tube 633 b may have an innerdiameter of about 0.8 mm and the outer diameter of inner tube 664 may beof about 0.78 mm.

Intermediate tube 633 b can be manufactured by an extrusion process inwhich the ID (internal diameter) has an appropriate tolerance to fitover the outer diameter of inner tube 664. Inner tube 664 andintermediate tube 633 b are assembled together such that lateral port612 is located in the horizontal opening 638 of intermediate tube 633 b.Thereafter the tubes 664 and 633 b are inserted into the hollow shaft663 and lateral port 612 can be attached to hollow shaft 663.

It should be noted that intermediate tube 633 b is not necessarily acomplete tube. While the distal portion of intermediate tube 633 bshould be of a tubular shape, its proximal portion may have othercross-sectional shapes such as a semilunar shape. Alternatively,proximal portion of intermediate tube 633 b may be implemented by a wireattached to its distal portion and exiting catheter 660 via proximalopening 665.

FIGS. 15A to 15C show longitudinal section views of a catheter 670according to a seventh preferred embodiment of the invention wherein theinner tube 674 is made movable by affixing it to a slidable sealingsleeve 679. In this preferred embodiment the distal end of balloon 611 ais attached to the inner tube 674 at distal attachment points 62 aprovided around the outer surface of a distal section of said innertube.

The structure, geometrical dimensions of elements of catheter 670designated by the same numerals, and the method of manipulating itslength and balloon's volume and shape, are much the same as thoseelements and manipulating method which were previously describedhereinabove and therefore will not be further discussed herein, for thesake of brevity.

As with previous embodiments of the invention the inner tube is disposedin the hollow interior of the catheter's hollow outer shaft 676 and acurved section 637 thereof comprising lateral port 612 protrudesoutwardly therefrom. A lateral opening 69 is provided on hollow outershaft 676 from which said curved section 637 of inner tube 674 isprotruding outwardly from hollow shaft 676. Lateral opening 69 is sealedby sealing sleeve 679 mounted over an outer surface of hollow outershaft 676. Sealing sleeve 679 is designed to tightly fit over the outersurface of hollow outer shaft 676, and to seal lateral opening 69 andthe attachment area between sealing sleeve 679 and the curved section637 of inner tube 674 protruding therefrom. Moreover, sealing sleeve isalso made slidable to allow its movement distally or proximally withinthe limits imposed by lateral opening 69.

In this way a movable inner tube 674 is obtained. The operator mayinflate (designated by arrows 67 a in FIG. 15A) balloon 611 a and moveinner tube distally or proximally by sliding sealing sleeve 679 overhollow shaft 676. Additionally or alternatively, a displacement rod 648may be employed for this purpose. Displacement rod 648 may be attachedto a proximal section of inner tube 674 and a proximal section thereofcan be made available to the operator via a proximal opening 675provided at the proximal end of hollow shaft 676. Proximal opening 675is designed to allow conveniently sliding displacement rod 648therethrough while providing suitable sealing thereof and preventingleakage of inflation fluid therefrom.

Lateral opening 69 is adjusted to allow moving inner tube 674 proximallyinto a state in which attachment point 62 a reaches the proximal end ofhollow shaft 676, and on the other hand, to allow moving inner tube 674sufficiently distally and enable stretching balloon 611 a to its fullestlength.

Sealing sleeve 679 can be manufactured by an extrusion and laser cuttingprocess from a plastomer or metallic type of material, preferably fromnylon or flexible stainless steel. The sealing and attachment of sealingsleeve 679 and the curved section 637 of inner tube 674 is preferablyobtained by bonding these parts together by thermo-bonding or any otheradhesive method such that they can slide together. The diameter ofsealing sleeve 679 is adjusted according to the geometrical dimensionsof hollow shaft 676. For example, if the diameter of hollow shaft isabout OD (outer diameter) 1.2 mm then the diameter of sealing sleeve ismade about ID 1.22 mm.

FIG. 15C demonstrates an implementation of catheter 670 a, similar tocatheter 670, wherein an inner sealing sleeve 677 is adapted to beinstalled in the hollow interior of hollow shaft 676. In thisimplementation inner sealing sleeve 677 is adapted to be pressed againstthe inner wall of hollow shaft 676 about the area of lateral opening 69and thereby to provide suitable sealing thereof. As in catheter 670illustrated in FIG. 15A, vertical section of inner tube 674 protrudesoutwardly via inner sealing sleeve 677 and may be accessed by theoperator via lateral port 612. The sealing and attachment of innersealing sleeve 677 and vertical section of inner tube 674 may beobtained using the same means described above with reference to catheter670.

Inner sealing sleeve 677 can be manufactured by an extrusion and lasercutting process from a plastomeric or metallic type of material,preferably from nylon or flexible stainless steel. The sealing andattachment of inner sealing sleeve 677 and the vertical section of innertube 674 is preferably obtained in a similar manner as was explainedhereinabove. The diameter of sealing sleeve 677 is adjusted according tothe geometrical dimensions of hollow shaft 676. For example, if thediameter of hollow shaft is about ID 1 mm then the diameter of innersealing sleeve is made about OD 0.98 mm.

All of the abovementioned parameters are given by way of example only,and may be changed in accordance with the differing requirements of thevarious embodiments of the present invention. Thus, the abovementionedparameters should not be construed as limiting the scope of the presentinvention in any way. In addition, it is to be appreciated that thedifferent tubes, balloons, shafts, and other members, describedhereinabove may be constructed in different shapes (e.g. having oval,square etc. form in plan view) and sizes from those exemplified in thepreceding description.

It should be noted that the different balloon catheter embodiments ofthe invention which were described hereinabove may be implemented withdifferent types of balloon enabling folding of the proximal section ofthe balloon, the distal section of the balloon, or both proximal anddistal sections of the balloon, as was exemplified hereinabove withreference to FIGS. 9D and 9E.

In particularly preferred embodiments of the RE catheter system of thepresent invention, the balloon shape and force resistancecharacteristics of the catheter tubing are as described hereinabove inconnection with the OTW systems, and exemplified in the following twoExamples.

EXAMPLES Example 1 Finite Element Analysis (FEA) of a Debris-CollectingBalloon for Use in the Present Invention

FEA is a computerized tool which was used to optimize the balloon designin order to improve its ability to fold in the desired way. The FE modeldescribes an inflated balloon which its edge is retracted, resulting infolding of the balloon. The simulation was performed on differentballoon designs and at varied inflation pressures, taking into accountthe mechanical properties of the balloon material, which was chosen tobe nylon 12 or pebax.

Assumptions:

i. The balloon is made of a homogenous and isotropic material.ii. The balloon's shape is symmetrical around its longitudinal axis.iii. The balloon's shape is symmetrical around its mid transverse axis.iv. The folding results in flexural stresses in the balloon material.Thus the mechanical properties (Modulus and Poisson Ratio) of thesubstance when flexed are taken into account in the FE analyses.

Methods:

a) The analyses were performed using a nonlinear Finite ElementsAnalysis (FEA) program MSC.MARC. This software allows assessment of thestructural integrity and performance of parts undergoing largedeformations as a result of thermal or structural load(www.mscsoftware.com).b) The analyses were nonlinear, assuming large displacements and takinginto account stiffness change due to geometry update and sequentialforces.c) The model was 2D axisymmetric.d) The model consisted of about 1000 nodes and 1000 2D solid elements.e) Constant pressure was applied from within the balloon on its walls,reflecting the inflation pressure. Simultaneously, gradually increasedaxial force was exerted to the edge of the balloon, results in itsfolding. The displacement of the balloon wall in the horizontal(longitudinal) axis was measured versus the applied force.f) The longitudinal axis of the balloon was kept fixed, while theballoon walls were free to move/fold as a result of the axial load.g) The balloon's specifications are listed in the following table:

Balloon Specifications Balloon length [mm] 20 Balloon Outer Diameter[mm] 3 Tube Outer Diameter [mm] 0.4 Balloon Body Wall Thickness [μm] 10Neck Wall Thickness [μm] 50 Tube Wall Thickness [μm] 100 Taperingvarying Material PET (Polyethylene Terephthalate) Mechanical PropertiesFlexural Modulus [Kg/mm²] 100 Flexural Yield Strength 8.15 [Kg/mm²]Poisson Ratio 0.4h) Four balloon designs were analyzed, wherein the differences reside inthe design of their tapering (see FIG. 6):

-   -   Standard 20° tapering    -   20° tapering with smooth round ending    -   Round ending    -   Round ending with initial retracting        i) The simulations were performed at five different inflation        pressures: 1, 3, 6, 9 and 12 atmospheres.

Results:

FIG. 7 shows the displacement vs. retracting force for the four balloonshapes at an inflation pressure of 6 atmospheres. Considering themaximal force required for collapse of the balloon, the Tapered-RoundEnding Balloon required the lowest force, whereas the Round EndingBalloons need the greatest force to collapse. The Tapered Ending Balloonis somewhere between them. The slope of the Tapered Ending Balloon inthe initial phase seems to be relatively moderate compared to the otherballoon configurations. The moderate slope indicates higher stiffness.In other words, higher force is required to induce a given displacement.The slope of the Tapered-Round Ending Balloon is the steepest one, andsuggests relatively high compliance to folding.

The balloon retracted shape vs. the original shape, at differentinflation pressures was also studied (results not shown). The resultsdemonstrated that the Tapered Ending Balloon is barely retracted,compared to the Round Ending Balloons which are retracted in a moresmooth and continuous fashion. This is in spite of the higher forcerequired to fold them.

CONCLUSION

From the above analyses it was concluded that the inflation pressure andthe balloon geometry have an important role in determining of therequired folding force and the folding style. It appears that a taperedballoon with a smooth round ending folds best and has a relatively lowretracting force, when compared to standard tapered balloon or a balloonwith a round ending.

Example 2 Determination of the Force that is Required in Order to Foldthe Balloon at Different Inflation Pressure Equipment and Materials: 3.0mm Nylon 12 Vestamid L2101F Balloon (Interface Associates 316079-1)

Glass tube with inner diameter of 3 mm.

Guidant HI-TORQUE CROSS-IT 200XT 0.014″ Guidewire.

Hounsfield Test Equipment Model TX0927, 50-N load cell. This computercontrolled testing machine enables determining tension, compression,shear, flexure and other mechanical and physical properties ofmaterials. The machine provides selection of test speeds and directionof travel. It can measure the force and displacement values and can alsographically display the test.Assouline Compressor type 1.5 HP.Fluid dispensing system Model 1500XL.

Procedure:

The balloon was inserted into a 3-mm glass tube, at straight position orinclined to 45°. A guidewire was inserted into the inner tube in orderto stabilize the folding motion. The balloon was inflated using acompressor and the inflation pressure was controlled by a dispenser. Theprocedure was performed at pressures ranging between 3-7 atm, withincrements of 1 atm. The balloon was folded using the Hounsfield Testmachine, by pulling the inner tube at speed of 100 mm/min up to 20 mm,and then pushing back at the same speed until the balloon was completelyunfolded.

Four tests were conducted at each pressure, to confirm that the resultscould be replicated.

Results:

The maximal force required for folding the balloon at each pressure ispresented in FIG. 8 The maximal force increases with the inflationpressure for both positions (straight and inclined) and ranges between2-3.5 N (200-350 gr) with increments vary between 0.2-0.4 N (20-40 gr)per step of 1 atm in pressure. Higher inflation pressure requiresgreater force to fold the balloon. The relationship is approximatelylinear (R²=0.98). The maximal forces are slightly lower for the inclinedposition; however, repeated tests at the straight position revealed thatthe lesser forces result from the material fatigue. To support thisassumption, visual examination of the balloon after 40 repeats showedthat the balloon material lost its flexibility and looked crumpled.

The above examples and description have of course been provided only forthe purpose of illustration, and are not intended to limit the inventionin any way. As will be appreciated by the skilled person, the inventioncan be carried out in a great variety of ways, employing more than onetechnique from those described above, all without exceeding the scope ofthe invention.

1. A balloon catheter comprising: an outer conduit having an outersurface; an inner conduit having an outer surface, the inner conduit issuitable for passage over a guide wire, the inner conduit is movablydisposed within the lumen of the outer conduit, wherein the distal tipof the inner conduit extends beyond the distal tip of the outer conduitat all times during operation of the catheter, and wherein the innerconduit is capable of being moved along its longitudinal axis inrelation to the outer conduit; a balloon, having a proximal margin and adistal margin, wherein the proximal margin of the balloon is attached tothe outer surface of the distal tip of the outer conduit and the distalmargin of the balloon is attached to the outer surface of the portion ofthe inner conduit that extends beyond the distal tip of the outerconduit, and wherein the distal and/or proximal end portion(s) of theballoon are capable of intussuscepting upon proximal movement of theinner conduit in relation to the outer conduit to form a cavity withinthe balloon, such that when the intussuscepted balloon is deflated, thecavity is enlarged trapping therewithin debris and/or particulate matterwithout the need for application of externally applied suction; and afluid port for the introduction of an expansion fluid into the annularspace formed between the inner surface of the outer conduit and theouter surface of the inner conduit and therefrom into the lumen of theballoon, and for the removal of the expansion fluid.
 2. The ballooncatheter according to claim 1, wherein the distal portion of the balloonis capable of intussuscepting upon proximal movement of the inner tubein relation to the outer tube.
 3. The balloon catheter according toclaim 1, wherein the inner and outer conduits are characterized by theirability to withstand axially directed forces in the range of between 2and 20 Newton without undergoing significant deformation.
 4. The ballooncatheter according to claim 3, wherein the inner and/or outer conduitsare constructed from a material selected from the group consisting of abiocompatible polymer, nylon, a braided nylon thread, a nylon threadthat has undergone orientation treatment, flexible stainless steeltubing, a polymer tube with metal mesh reinforcement, reinforced Pebax®,polyurethane and PET.
 5. The balloon catheter according to claim 1,wherein the balloon is characterized by having, in its inflated state, ashape which is capable of guiding the intussuscepting of the distaland/or proximal portion(s) thereof upon proximal movement of the innerconduit in relation to the outer conduit.
 6. The balloon catheteraccording to claim 5, wherein the balloon is characterized by having, inits inflated state, a distal taper with a rounded distal extremity. 7.The balloon catheter according to claim 5, wherein the balloon ischaracterized by having, in its inflated state, a proximal taper with arounded proximal extremity.
 8. The balloon catheter according to claim1, also including an automatic pressure regulating mechanism forautomatically resolving overpressure conditions within the annular spaceand the balloon upon the proximal movement of the inner conduit inrelation to the outer conduit.
 9. The balloon catheter according toclaim 8, wherein the automatic pressure regulating mechanism is selectedfrom, an overpressure valve in fluidic communication with the annularspace; a syringe-like structure, having a barrel portion and a plunger,positioned at the proximal end of the catheter system, wherein thebarrel portion of the syringe-like structure is formed by an expandedportion of the outer conduit, and wherein the plunger of thesyringe-like structure co-axially surrounds the proximal end of theinner conduit, and is affixed thereto, an inflatable member attached tothe opening of an outlet formed in the outer conduit, the outer tube, orportions thereof, being inflatable such that over-pressure conditionsmay be resolved by its expansion, and any combinations thereof.
 10. Theballoon catheter system according to claim 8, wherein the automaticpressure regulating mechanism comprises an overpressure valve fordischarging inflation fluid whenever overpressure conditions develop inthe lumen of the outer conduit.
 11. The balloon catheter systemaccording to claim 8, wherein the automatic pressure regulatingmechanism comprises an overpressure valve for discharging inflationfluid whenever the pressure in the balloon and the inner lumen of theouter conduit reaches a set point.
 12. The balloon catheter systemaccording to claim 8, wherein the set point is in the range of 1-25atmospheres.
 13. The balloon catheter system according to claim 8,wherein the automatic regulating mechanism comprises a syringe-likestructure, having a barrel portion and a plunger, positioned at theproximal end of the catheter system, wherein the barrel portion of thesyringe-like structure is formed by an expanded portion of the outerconduit, and wherein the plunger of the syringe-like structureco-axially surrounds the proximal end of the inner conduit, and isaffixed thereto, wherein when the inner conduit is proximally pulled theplunger moves proximally within the barrel portion to automaticallyaccommodate excess inflation fluid ejected from the balloon during theintussuscepting of the balloon, to prevent overpressure conditions fromdeveloping within the balloon.
 14. The balloon catheter system accordingto claim 1, wherein the catheter also includes a graduated scale formedon the inner conduit for determining the length of the inner conduitthat has been proximally retracted from the outer conduit.
 15. Theballoon catheter system according to claim 1, wherein the catheter alsoincludes a locking mechanism for locking the inner conduit to preventit's axial movement within the outer conduit and for releasing the innerconduit to enable its axial movements within the outer conduit.
 16. Theballoon catheter system according to claim 15, wherein the lockingmechanism comprises a safety lock sealingly and movably disposed withina tight orifice formed in the proximal end of the outer conduit andattached U-shaped gripping clip attached to the safety lock and movablydisposed within the outer conduit, the gripping clip is adapted forgripping the outer surface of the inner conduit when the safety lock ispushed radially inwardly towards the inner conduit to prevent proximaland distal movement of the inner conduit relative to the outer conduitand to release the inner conduit when the safety lock is pulled radiallyoutwardly away from the inner conduit to enable proximal and distalmovement of the inner conduit relative to the outer conduit.
 17. Theballoon catheter system according to claim 1, wherein the catheter isadapted to operate within a predetermined pressure range of 1-25atmospheres.
 18. The balloon catheter system according to claim 1,wherein the inner conduit, the balloon and the outer conduit have ashape selected from the group consisting of a tubular shape, an ovalshape and a square shape.
 19. A method for collecting debris from aninternal passage of a mammalian subject, the method comprises the stepsof: a) inserting a balloon catheter as defined in claim 1 into theinternal passage, and advancing the catheter until the distal tipthereof has reached the site, at which it is desired to collect debris;b) inflating the balloon with expansion fluid; c) pulling the innerconduit of the catheter in a proximal direction, causing theintussuscepting of the distal and/or proximal end(s) of the balloon; d)deflating the balloon, thereby forming a cavity into which debris iscollected and entrapped without the need of applying of suction from anexternal source; and e) removing the balloon catheter from the internalpassage of the subject, together with the entrapped debris.
 20. Themethod according to claim 19, wherein the internal passage is a bloodvessel.